Hydrofluoroalkanes as cleaning and degreasing solvents

ABSTRACT

Hydrofluoroalkanes useful as solvents, especially for vapor degreasing and solvent cleaning, are one or many of the following formulae: CHF2-X-(CHF)n-X-Ywherein X is selected from the group consisting of CHF, CF2 and CH2, Y is CH3, and n is 0, 1 or 2.

FIELD OF THE INVENTION

This invention relates to vapor degreasing and solvent cleaning and moreparticularly relates to the use of certain hydrofluoroalkanes for vapordegreasing and solvent cleaning.

BACKGROUND

Vapor degreasing and solvent cleaning with fluorocarbon-based solventshave found widespread use in industry for the degreasing and otherwisecleaning of solid surfaces, especially intricate parts anddifficult-to-remove soils.

In its simplest form, vapor degreasing or solvent cleaning comprisesexposing an object to be cleaned to the vapors of a boiling solvent.Vapors condensing on the object provide clean distilled solvent to washaway grease or other contamination. Final evaporation of solvent fromthe object leaves behind no residue as would be the case where theobject is simply washed in liquid solvent.

In situations where it is difficult to remove soils such as whereelevated temperatures are necessary to improve the cleaning action ofthe solvent, or for large volume assembly line operations where thecleaning of metal parts and assemblies must be done efficiently andquickly, the conventional operation of a vapor degreaser comprisesimmersing the part to be cleaned in a sump of boiling solvent whichremoves the bulk of the soil, thereafter immersing the part in a sumpcontaining freshly distilled solvent at near room temperature, andfinally exposing the part to solvent vapors over the boiling sump whichcondense on the cleaned part. In addition, the part can also be sprayedwith distilled solvent before final rinsing.

Cold cleaning is another application where a number of solvents areused. In most cold cleaning applications, the soiled part is eitherimmersed in the fluid or wiped with cloths or similar objects, soaked insolvents and allowed to air dry.

Solvents comprising fluorocarbons are, of course, well-known. Inparticular, trichlorotrifluoroethane (CFC-113) has attained widespreaduse in recent years as an effective, non-toxic and non-flammable agentuseful in degreasing applications and other solvent cleaningapplications. The problem with chlorofluorocarbons, known as CFCs, suchas CFC-113, is that they are believed to cause environmental problems inconnection with the ozone layer in the earth's atmosphere. Therefore,the art is seeking new fluorocarbon-based materials which provide thecleaning advantages of the known chlorofluorocarbons but which do nothave an adverse effect on the ozone layer of the earth's atmosphere.Mathematical models substantiate that hydrofluorocarbons which do notcontain chlorine will not adversely effect atmospheric chemistry becausethey are non-ozone depleting and would contribute negligibly to globalwarming when compared to CFCs such as CFC-113.

It is known from European Patent Application No. 043145881, publishedJun. 12, 1991, that certain fluorinated aliphatic hydrocarbons may beused as cleaning compositions alone or in admixture with an organicsolvent. The present invention provides a new class of fluorinatedaliphatic hydrocarbons which do not contain chlorine and which areuseful as degreasers and solvents.

The present invention provides a specific group of hydrofluoroalkanesuseful as cleaning and degreasing solvents, which hydrofluoroalkanes arecharacterized by being non-flammable, having a boiling point in therange of 30° to 120° C. and fluorinated to the extent of 67 to 75percent based on atomic weight. More particularly, the present inventionprovides a select group of solvents for cleaning and degreasing whichare hydrofluoroalkanes characterized as containing from 3 to 6 carbonatoms, from 67 to 75 percent of fluorination on said carbon atoms basedon atomic weight, and having a boiling point in the range of 30°-120° C.The present invention also provides methods for cleaning and/ordegreasing components and substrates which comprises treating saidcomponents and/or substrates with an effective amount of a solventcomprising one or more hydrofluoroalkanes of this invention.

DESCRIPTION OF THE INVENTION

The hydrofluoroalkanes of the present invention have good solvent power,but do not contribute to ozone depletion. The compounds are alsonon-flammable and do not exhibit any flash point when tested by the TagOpen Cup Test Method--D-ASTM 1310-86 and Tag Closed Test Method--D-ASTM56-82.

The present invention provides solvent compositions comprising certainstraight chain hydrofluoroalkanes, i.e., aliphatic hydrocarbons whichcontain only hydrogen and fluorine as substituents. Thehydrofluoroalkanes of the present invention may be characterized asbeing one or more fluorinated hydrocarbons as set forth hereinafter.

A preferred group of fluorinated hydrocarbons of this invention arethose of the following formula:

    CF.sub.2 H--X--(CHF).sub.n --Y

wherein n is 0, 1 or 2, and X is CHF, CF₂ or CH₂, and Y is CF₃ or CH₃.

A further preferred group consists essentially of the followingfluorinated hydrocarbons which may be used alone or in combination asthe cleaning agent in the method of the invention:

    CHF.sub.2 CHFCF.sub.2 H CH.sub.3 CHFCF.sub.2 CF.sub.2 CF.sub.3

    CF.sub.3 CF.sub.2 CH.sub.2 CH.sub.2 F CHF.sub.2 (CF.sub.2).sub.3 CHF.sub.2

    CF.sub.3 CH.sub.2 CF.sub.2 CH.sub.2 F CF.sub.3 CH.sub.2 CHFCH.sub.2 CF.sub.3

    CF.sub.3 CF.sub.2 CH.sub.2 CH.sub.2 CF.sub.3 CF.sub.3 CH.sub.2 CH.sub.2 CF.sub.3

    CF.sub.3 CF.sub.2 CH.sub.2 CH.sub.2 CF.sub.2 CF.sub.3 CHF.sub.2 CF.sub.2 CF.sub.2 CF.sub.2 CF.sub.3

The solvents and degreasers of the invention may be prepared byfollowing the synthesis disclosed in F. A. Bloshchitso, A. I. Burmakov,b.v. Kunshenko, L. A. Alekkseeva and L. M. Yugopolski "Reaction ofhydroxy and carbonyl compounds with sulfur tetrafluoride. XIV. Reactionof aliphatic oxocarboxylic acid with SF₄," Zh. Org. Khim., Volume 21,No. 7, 1985, pages 1414-1420 (English translation can be found in theRussian Journal of Organic Chemistry, Volume 21,. No. 7, 1985, pages1286-1291). The hydrofluoroalkanes of the invention can also be preparedaccording to Zh. Org. Khim, 1980, 1401-1408 and 1982, 946 and 1168; Zh.Org. Khim. 1988, 1558; J. Chem. Soc. Perk. 1, 2258 (1980); J. Chem. Soc.Perk. Trans. 2, 1713 (1983); J. Chem. soc. C 1969, 1739; J. Chem. Soc.1949, 2860; Zh. Anal. Khim. 1981 36 (6) 1125 (1181); J. Flourine chem.1979, 325; Izv. Akad. Nauk SSSR, Ser. Khim. 1980, 2117 (in Russian);Rosz. Chem. 1974, (48), 1697 and J.A.C.S. 67, 1195 (1945); 72, 3577(1950) and 76, 2343 (1954). Other methods for the preparation of thesolvents and degreasers will readily occur to those skilled in the art.

The synthesis of the compounds described here is highly varied,depending on the structure of the molecule. However, general procedureswill be applicable to the synthesis of many of these compounds. Forexample, the reduction of fluoroalkynes of the formula, RC═CR where R isH or F such as CF₃ CF₂ C═CCF₃, provides access to compounds containingthe --CH₂ CH₂ -grouping.

Perfluoralkyl iodides, R_(f) I, are readily available commercially andare excellent raw materials for a variety of HFCs. For example, theR_(f) I can be added to olefins at about 200° C. The addition to vinylfluoride gives a mixture of a R_(f) CHFCH₂ I and R_(f) CH₂ CHFI.Reduction of these adducts with e.g., Zn, gives a mixture of R_(f) CH₂CH₂ F and R_(f) CHFCH₃ which can be separated by distillation. Thus, CF₃CF₂ CHFCH₃, CF₃ CF₂ CF₂ CH₂ CH₂ F and similar compounds can be prepared.

Tosylation of commercially available fluorinated alcohols followed byreaction with KF gives compounds containing the --CH₂ F group. In thismanner, HCF₂ CF₂ CR₂ CF₂ CH₂ F (from commercially available HCF₂ CF₂ CF₂CF₂ CH₂ OH), CH₂ F CF₂ CF₂ CF₂ CH₂ F (from HOCH₂ CF₂ CF₂ CF₂ CH₂ OH),and HCF₂ CF₂ CF₂ CF₂ CH₂ F (from HCF₂ CF₂ CF₂ CF₂ CH₂ OH) can beprepared. If the tosylate is first reacted with KI and then subsequentlyreduced with Zn, compounds such as HCF₂ CF₂ CF₂ CF₂ CH₃ can be prepared.

Compounds containing the CH₂ CHF-- moiety can be prepared either by theaddition of HF to the corresponding olefin, or addition of HF to thecorresponding alkyne (to give the --CH═CHF-- group) followed byreduction. In this way, CF₃ CF₂ CH₂ CH₂ F can be prepared fromcommercially available CF₃ CF₃ CH₂ ═CH₂, for example.

The addition of two fluorines to olefinic carbons can be effected bylead tetraacetate and HF. Thus, CF₃ CF₂ CF₂ CH═CH₂ can be converted intoCF₃ CF₂ CF₂ CHFCH₂ F.

Additional examples of various methods for preparing HFC's andfluorinated intermediates, in addition to those given above, can befound in specialized texts such as the laboratory manual andcomprehensive compilation of M. Hudlicky, "Chemistry of Organic FluorineCompounds", 2nd edition, Ellis Horwood Ltd., Chicester, UK, 1992.

Additives such as rust inhibitors, surfactants, corrosion inhibitors,decomposition inhibitors, acid scavengers, antioxidants, and emulsifiersin effective amounts (0.01 to 10 wt. %) may be added to the solvents toobtain additional desired properties. For example, alcohols can be addedwhich enable the solvents to be used to remove solder fluxes fromprinted circuit boards. Inhibitors may be added to the solvent ineffective amounts to inhibit decomposition react within undesirabledecomposition products of the composition and/or prevent corrosion ofmetal surfaces. Any or all of the following classes of inhibitors may beemployed in the invention: alkanols having 4 to 7 carbon atoms,nitroalkanes having 1 to 3 carbon atoms, 1,2-epoxyalkanes having 2 to 7carbon atoms, phospshite esters having 12 to 30 carbon atoms, ethershaving 3 to 4 carbon atoms, ketones having 3 to 5 carbon atoms, andamines having 5 to 8 carbon atoms. Other suitable inhibitors willreadily occur to those skilled in the art. The inhibitors may be usedalone or as mixtures in any proportion. Typically, up to about 2 percentof inhibitor based on the total weight of the mixture may be used.

The cleaning method of the invention removes most contaminants from thesurface of a substrate by use of an effective amount of one or moresolvents of the invention. By "effective amount" is meant the amount ofsolvent necessary to dissolve and remove the contaminant. for example,the present method removes organic contaminants such as mineral oils andsynthetic oils from the surface of a substrate. Under the term "mineraloils," both petroleum-based and petroleum-derived oils are included.Lubricants such as engine oil, machine oil, and cutting oil are examplesof petroleum-derived oils. The term "synthetic oils" embraces oils whichdo not contain petroleum-derived products, e.g., silicone oils.

The solvents of the invention also remove water from the surfaces ofsubstrates. The method may be used in the single-stage or multistagedrying of objects.

By extensive testing, it has been found that HFCs with at least 67% byweight fluorine generally do not have flashpoints. Similarly, it hasbeen found that HFCs with more than 75% fluorine by weight arerelatively poor solvents, especially for difficult-to-remove soils.Furthermore, the estimated solubility parameters, δ, which areindicators of solvent power, generally are very low (less than 6.2) whenthe weight percent fluorine is high. Thus, the preferred compounds have69-73 weight percent fluorine. This range of fluorine is low enough toprovide good solvency and high enough to prevent flammability, and evenallows small amounts of (flammable) beneficial additives to beincorporated without rendering the mixture flammable.

Although no solvent can clean all types of soils, the best solvents arethose which have solvent properties which permit the cleaning of avariety of soils, including both polar soils, such as synthetic andsemi-synthetic oils, and non-polar soils such as petroleum or mineraloils. The HFCs of this invention have a good balance of solventproperties, as judged by the polar and non-polar contributions to thetotal solubility parameter δ. The degree of non-polar and polarcontributions will vary, depending on the structure and percentfluorine. For example, the compound CH₂ FCHFCHFCF₂ CF₃ is relativelypolar, and would be especially good for removing polar soils.

We have also found that the % fluorine generally affects the atmosphericlifetime. Although this depends on the distribution of hydrogens in themolecule, there is a trend indicating increased atmospheric lifetimewith increasing fluorine content. Thus, butane, pentane, and hexane HFCswith only 1 or 2 hydrogens (>75% fluorine) have undesirably longlifetimes.

The HFCs of this invention have boiling points in the range of about 41°to 91° C. This range of boiling points provides a balance of two factorsrelated to their use in solvent and cleaning applications. The first isthat high boiling compounds require considerable energy consumption tomaintain reflux, which is very commonly used in vapor cleaning anddegreasing. However, if the boiling point is too low, substantial lossesmay result through evaporation and difficulty in condensing the vapors.

Thus, the HFCs of this invention provide an exceptional balance of themost desirable properties required for solvent cleaning, compared to thethousands of other HFCs that could be considered for solventapplications.

The method of the present invention may be used to clean the surface ofinorganic and organic substrates. Examples of inorganic substratesinclude metallic substrates, ceramic substrates, and glass substrates.Examples of organic substrates include polymeric substrates such aspolycarbonate, polystyrene, and acrylonitrile-butadiene-styrene (ABS).The method also cleans the surface of natural fabrics such as cotton,silk, fur, suede, leather, linen, and wool. The method also cleans thesurface of synthetic fabrics such as polyester, rayon, acrylics, nylon,and blends thereof, and blends of synthetic and natural fabrics. Itshould also be understood that composites of the foregoing materials maybe cleaned by the present method.

The method of the invention may be used in vapor degreasing, solventcleaning, cold cleaning, dewatering, and dry cleaning. In these uses,the object to be cleaned is immersed in one or more stages in the liquidand/or vaporized solvent or is sprayed with the liquid solvent. Elevatedtemperatures, ultrasonic energy, and/or agitation may be used tointensify the cleaning effect.

In spraying applications, the solvents may be sprayed onto a surface byusing a propellant (aerosol) or by some mechanical device. Suitablepropellants include hydrochlorofluorocarbons like chlorodifluoromethane,hydrofluorocarbons such as 1,1,1,2-tetrafluoroethane, ethers likedimethyl ether and hydrocarbons like butane and isobutane.

The solvents of the invention are characterized as indicated above by alow or no flash point, and for the most part have a lifetime of lessthan ten years. Their solubility parameters range from 6.0 to 7.5 in(Calories/cc)^(1/2).

The following Tables set forth preferred hydrofluoro carbons of thepresent invention including the predicted boiling point, the predictedlifetime in years, the calculated solubility parameters and the percentfluorine.

                  TABLE I                                                         ______________________________________                                                                        Est.                                                         Est.   Est.      Solubility                                    Chemical       B.P.   Lifetime  Parameters                                    Formula        (°C.)                                                                         (Years)   (cal.cc).sup.2                                                                        % F                                   ______________________________________                                        CF.sub.3 CF.sub.2 (CHF).sub.2 CH.sub.3                                                       61.7   ≦10                                                                              7.4     67.1                                  CF.sub.3 CF.sub.2 CHFCH.sub.2 F                                                              70     ≦10                                                                              7.4     67.1                                  CHF.sub.2 CH.sub.2 CF.sub.2 CHF.sub.2                                                        55.7   ≦10                                                                              6.4     68.6                                  CF.sub.3 (CHF).sub.2 CH.sub.2 F                                                              50.8   ≦10                                                                              7.3     68.6                                  CF.sub.3 (CF.sub.2).sub.3 CH.sub.2 CH.sub.3                                                  71     ≦10                                                                              6.7     68.9                                  CF.sub.3 (CF.sub.2).sub.2 (CHF).sub.2 CH.sub.3                                               86     ≦10                                                                              7.5     68.9                                  CH.sub.2 FCH.sub.2 CF.sub.2 CF.sub.2 CF.sub.3                                                60.7   ≦10                                                                              6.6     70.0                                  CF.sub.2 HCH.sub.2 CHFCF.sub.2 CF.sub.3                                                      74.6   ≦10                                                                              7.4     70.0                                  CH.sub.2 FCHFCHFCF.sub.2 CF.sub.3                                                            75.5   ≦10                                                                              7.4     70.0                                  CH.sub.2 FCF.sub.2 CH.sub.2 CF.sub.2 CF.sub.3                                                71.6   8-15      6.6     70.0                                  CF.sub.3 (CF.sub.2).sub.3 CHFCH.sub.3                                                        75.4   ≦10                                                                              6.8     71.4                                  CF.sub.3 (CF.sub.2).sub.3 CH.sub.2 CH.sub.2 F                                                85.8   ≦10                                                                              6.8     71.4                                  CH.sub.2 FCHFCF.sub.2 CF.sub.3                                                               38     ≦10                                                                              6.5     72.0                                  CF.sub.2 HCHFCHFCF.sub.3                                                                     51.9   ≦10                                                                              7.5     72.0                                  CF.sub.3 (CF.sub.2).sub.2 CHFCH.sub.2 F                                                      62.3   ≦10                                                                              7.4     73.0                                  CF.sub.3 CF.sub.2 CHFCH.sub.2 CF.sub.3                                                       65.3   8-20      7.4     73.0                                  CF.sub.3 CHFCH.sub.2 CF.sub.2 CF.sub.3                                                       66.5   8-20      7.4     73.0                                  CF.sub.3 (CHF).sub.3 CF.sub.3                                                                77.0   8-20      7.4     73.0                                  CF.sub.3 (CF.sub.2)CH.sub.2 CHF.sub.2                                                        63.6   8-15      6.5     73.0                                  CF.sub.3 CF.sub.2 CHFCF.sub.2 CH.sub.2 F                                                     68.1   8-15      7.4     73.0                                  CF.sub.3 CHF(CF.sub.2).sub.2 CF.sub.3                                                        70.3   8-15      7.4     73.0                                  CHF.sub.2 (CF.sub.2).sub.2 CH.sub.2 F                                                        69.8   8-15      6.5     73.0                                  CHF.sub.2 CHF(CF.sub.2).sub.3 CF.sub.3                                                       87.1   ≦10                                                                              6.4     74.0                                  CHF.sub.2 CH.sub.2 (CF.sub.2).sub.3 CF.sub.3                                                 88.7   8-20      6.4     74.0                                  CF.sub.3 CH.sub.2 CHF(CF.sub.2).sub.2 CF.sub.3                                               89.5   8-15      7.3     74.0                                  CF.sub.3 (CF.sub.2).sub.2 CH.sub.2 CHFCF.sub.3                                               84.9   8-15      7.3     74.0                                  CF.sub.3 CF.sub.2 CHFCHF.sub.2                                                               37.4   8-15      6.0     75.0                                  CH.sub.2 F(CF.sub.2).sub.3 CF.sub.3                                                          50.8   8-20      6.8     75.0                                  CF.sub.2 HCHF(CF.sub.2).sub.2 CF.sub.3                                                       61.7   8-20      6.0     75.0                                  CF.sub.3 CF.sub.2 CHFCHFCF.sub.3                                                             63.3   8-20      6.8     75.0                                  CF.sub.3 (CF.sub.2).sub.4 CH.sub.2 F                                                         75.9   8-20      6.6     76.0                                  CF.sub.3 (CF.sub.2).sub.3 CHFCHF.sub.2                                                       86.8   8-20      7.4     76.0                                  CF.sub.3 CHFCF.sub.2 CHFCH.sub.3                                                             68.0   ≦10                                                                              7.4     67.1                                  CF.sub.3 CHFCHFCF.sub.2 CH.sub.3                                                             72.9   8-20      7.4     67.1                                  CF.sub.3 CF.sub.2 CH.sub.2 CHFCH.sub.2 F                                                     75.2   ≦10                                                                              7.4     67.1                                  CF.sub.3 CHFCF.sub.2 CH.sub.2 CH.sub.2 F                                                     76.8   ≦10                                                                              7.4     67.1                                  CF.sub.3 CHFCH.sub.2 CF.sub.2 CH.sub.2 F                                                     83.1   ≦10                                                                              7.4     67.1                                  CF.sub.3 CH.sub.2 CF.sub.2 CHFCH.sub.2 F                                                     84.2   8-15      7.4     67.1                                  CF.sub.3 CH.sub.2 CHFCF.sub.2 CH.sub.2 CH.sub.2 F                                            85.4   ≦10                                                                              7.4     67.1                                  CF.sub.3 (CHF).sub.3 CH.sub.2 F                                                              89.1   ≦10                                                                              7.4     67.1                                  CF.sub.3 CH.sub.2 CH.sub.2 CF.sub.2 CHF.sub.2                                                80.4   ≦10                                                                              6.6     67.1                                  CF.sub.3 (CHF).sub.2 CH.sub.2 CHF.sub.2                                                      86.5   ≦10                                                                              7.4     67.1                                  CF.sub.3 CHFCH.sub.2 CHFCHF.sub.2                                                            87.7   ≦10                                                                              7.4     67.1                                  CF.sub.3 CH.sub.2 (CHF).sub.2 CHF.sub.2                                                      90.4   ≦10                                                                              7.4     67.1                                  CH.sub.2 FCH.sub.2 (CF.sub.2).sub.2 CHF.sub.2                                                79.7   ≦10                                                                              6.6     67.1                                  CH.sub.2 F(CF.sub.2).sub.2 CH.sub.2 CHF.sub.2                                                87.1   ≦10                                                                              6.6     67.1                                  CH.sub.2 FCF.sub.2 CH.sub.2 CF.sub.2 CHF.sub.2                                               87.2   8-15      6.6     67.1                                  CHF.sub.2 (CF.sub.2).sub.2 CHFCH.sub.3                                                       69.2   ≦10                                                                              7.4     67.1                                  CH.sub.2 FCHFCF.sub.2 CF.sub.2 CH.sub.2 F                                                    85.8   ≦10                                                                              7.4     67.1                                  CH.sub.2 FCF.sub.2 CHFCF.sub.2 CH.sub.2 F                                                    88.1   ≦10                                                                              7.4     67.1                                  CF.sub.3 CF.sub.2 (CH.sub.2).sub.2 CHF.sub.2                                                 72.5   ≦10                                                                              6.6     67.1                                  CF.sub.3 (CH.sub.2).sub.2 CHFCF.sub.3                                                        72.9   ≦10                                                                              7.4     67.1                                  CH.sub.2 F(CF.sub.2).sub.3 CH.sub.3                                                          65.4   8-15      6.6     67.1                                  CHF.sub.2 CF.sub.2 CHFCH.sub.2 F                                                             55.3   ≦10                                                                              7.3     68.6                                  CF.sub.3 CHFCH.sub.2 CHF.sub.2                                                               50.8   ≦10                                                                              7.3     68.6                                  CF.sub.3 CH.sub.2 CHFCHF.sub.2                                                               53.0   ≦10                                                                              7.3     68.6                                  CH.sub.2 F(CF.sub.2).sub.2 CH.sub.2                                                          49.2   ≦10                                                                              6.3     68.6                                  CHF.sub.2 (CF.sub.2).sub.2 CH.sub.3                                                          35.8   10-30     6.5     68.6                                  CH.sub.2 FCHHFCF.sub.2 CHFCF.sub.3                                                           80.1   8-15      7.4     70.1                                  CF.sub.2 HCFHCH.sub.2 CF.sub.2 CF.sub.3                                                      77.9   ≦10                                                                              7.4     70.1                                  CF.sub.3 CHFCH.sub.2 CHFCF.sub.3                                                             76.2   8-30      6.6     70.1                                  CH.sub.2 FCHF(CF.sub.2).sub.2 CF.sub.2 H                                                     81.3   ≦10                                                                              7.4     70.1                                  CF.sub.3 (CF.sub.2).sub.2 (CH.sub.2).sub.2 CF.sub.3                                          88.3   8-15      6.8     71.4                                  CF.sub.3 CF.sub.2 (CH.sub.2).sub.2 CF.sub.2 CF.sub.3                                         89.0   8-15      6.8     71.4                                  CHF.sub.2 (CF.sub.2).sub.2 CHFCHF.sub.2                                                      80.7   8-15      7.4     73.0                                  CF.sub.3 CHFCF.sub.2 CF.sub.2 CF.sub.3                                                       46.8   8-15      7.4     77.4                                  ______________________________________                                    

The following Table II sets forth a particularly preferred group offluorinated hydrocarbons for use in the invention:

                  TABLE II                                                        ______________________________________                                                             Est.     Est.                                            Chemical    Est.     Lifetime Solubility                                      Formula     B.P. °C.                                                                        (Years)  Parameters                                                                             % F                                    ______________________________________                                        CH.sub.3 CF.sub.2 CF.sub.2 CF.sub.2 H                                                     68       10-20    6.6      70.0                                   CHF.sub.2 CHFCHF.sub.2                                                                    41        5       6.4      70.9                                   CHF.sub.2 (CF.sub.2).sub.2 CHF.sub.2                                                      43.0     16(M)    6.0      75.0                                   CF.sub.3 CH.sub.2 CHFCH.sub.2 CF.sub.3                                                    85        6-15    7.4      67.1                                   CF.sub.3 CH.sub.2 CH.sub.2 CF.sub.3                                                       25        8-15    6.3      68.6                                   CF.sub.3 CF.sub.2 CH.sub.2 CH.sub.2 CF.sub.3                                              44.5-45  11       6.1      70.4                                   CHF.sub.2 CHFCHFCHF.sub.2                                                                 62-68    2-4      6.4      68.7                                   CF.sub.3 CF.sub.2 CH.sub.2 CH.sub.2 F                                                     44-46    2-4      6.5      68.7                                   CHF.sub.2 CHFCF.sub.2 CH.sub.2 F                                                          58-70    5-8      7.3      68.7                                   ______________________________________                                    

A further preferred group of fluorinated hydrocarbons are those of theformula:

    CF.sub.3 CH.sub.2 CF.sub.2 CH.sub.2 F

    CHF.sub.2 CHFCF.sub.2 CF.sub.2 CF.sub.2 H

    (CF.sub.3 CF.sub.2 CHF.sub.2)

    CFH.sub.2 CF.sub.2 CF.sub.2 CH.sub.2 F ##STR1##

EXAMPLE I

1,1,2,2,3,3,4,4,5-Nonafluoropentane HCF₂ CF₂ CF₂ CF₂ CH₂ F)

The alcohol (H(CF₂)₄ CH₂ OH, 104 g), 88 g tosyl chloride and 150 mLwater were stirred mechanically and heated to 50° C. A solution of 20 gNaOH in 80 mL water was added over 0.5 h, keeping the temperature below65° C. Stirring and heating were continued until the pH was neutral. Themixture was cooled and extracted with CH₂ Cl₂. The organic layer waswashed with 50 mL aq. ammonia, water, and dried over MgSO. Distillationgave 115 g colorless liquid, bp 110°-115° C. at 0.075 mm Hg (66% yield).

The above tosylate (301.5 g), 600 mL NMP, and 100 g KF were heated at195° C. for 6 h to give 114.2 g of desired product; 6 C purity, 96%.Re-distillation provided 90% pure material, bp 82°-83.5° C. ¹ H NMR:5.97 (tt, 1H) and 4.67 (dt, 2H) ppm. %F=73.

EXAMPLE II

1,1,1,4,4,4-Hexafluoro-2-(trifluoromethyl)butane

A 300 mL autoclave was charged with 21.0 g (0.1 mol)4,4,4-trifluoro-3-(trifluoromethyl)butyric acid (prepared byhydrogenation and hydrolysis of commercially available ethyl4,4,4-trifluoro-3-(trifluoromethyl)crotonate), 25 mL cyclohexane, and 38g (0.35 mol) SF₄. The contents were heated to 65°-70° C. for 3 days,vented through a KOH scrubber, and poured into a separatory funnelcontaining 40 mL water. The aqueous layer was extracted with 2×25 mLportions of cyclohexane, and the combined organic layers distilled. Anazeotrope of the desired product and cyclohexane was obtained (bp 41°-2°C.), which contained about 20% cyclohexane. The desired HFC was obtainedin 23% yield following extraction with light mineral oil anddistillation. A second distillation provided material of 99% purity, bp43°-44° C. 1H NMR (CDC13): δ 3.25 (m, 1 H) and 2.63 (dq, 2 H); 19 F NMR:67.3 (3 F) and 69.5 (5F) ppm. %F=70.

EXAMPLE III

1,1,2,2,3,3,4,4-Octafluoropentane

The tosylate of 2,2,3,3,4,4,5,5-octafluoropentanol was preparedaccording to Example I. The tosylate (117.2 g), 200 mL diethylene glycol(dried over 4 A sieves) and 70 g NaI were heated for 4 h to 150°-165° C.under a partial vacuum (100-120 mm Hg). The cold trap contained 73 g(93% pure) iodide, and after washing with water, weighed 70.3 g. Itdistilled at 64°-65° C. at 54 mm Hg.

The iodine (72.4 g) prepared as described above, was added to 63 mLtributyltin hydride over 2 h with stirring at <40° C., and the productwas then distilled directly from the reaction mixture (38 g, 97% pure).Another distillation increased the purity to 99.5% (bp 67°-8° C.). 1HNMR: δ 1,83 (t, 3 H, J=18 Hz), 6.05 (tt, 1H, J-5 and 52 Hz). %F=73.

EXAMPLE IV

1,1,1,2,2,5,5,6,6,6-Decafluorohexane-(CF₃ CF₂ CH₂ CH₂ CF₂ CF₃)

The reactor in this Example consisted of a 1.25 inch diameter Pyrex tubeheated by means of electrical heating tape, and an internal thermocoupleto measure the temperature inside the tube. The reactor was packed witha mixture of 50 cc 0.5% Pd/Al₂ O₃ (1/8 inch pellets) and 100 cc glasshelices for a total bed volume of 150 cc. Effluent from the reactor wascondensed into cold traps maintained at -30° C. and -78° C. Hydrogen waspassed into the tube at 155 mL/min, while CF₃ CF₂ CCl₂ CCl₂ CF₂ CF₃ wasmetered into the top of the vertically mounted reactor at a rate ofabout 10 g/h. The temperature inside the reactor during the reductionwas 202°-206° C. After a total reaction time of 3.75 h (38.1 g of theCFC added), 20.15 g of product was collected in the cold traps, whichwas 99% pure by GC. It was identified as CF₃ CF₂ CH₂ CH₂ CF₂ CF₃, bp 66°C. (80% yield). 1H NMR (CDC13): δ 2.45 (t): 19F NMR: -87 and -122.5 ppmin a 3:2 ratio; MS: 247 (P-F) and base peak at m/e 177 (P-HF and CF₃),bp 66° C., %F=71.4.

EXAMPLE V

1,1, 1,3,5,5,5-Heptafluoropentane

1,1,1,3,3,5,5,5-Octafluoropentane (total 16.6 g, 0.0768 mol) wasintroduced at a rate of 0.16 g per minute into the top of a verticallymounted Monel tube reactor (1 inch diameter) heated electrically to 365°C. The reactor was packed with 75 cc of 12-20 mesh Darco activatedcarbon. Nitrogen (50 cc/min) was passed through the reactor along withthe organic material. Gases exiting the reactor were passed through anaqueous KOH scrubber followed by a cold trap at -78° C. A total of 11.45g was collected in the cold trap. Analysis of this material by gaschromatography indicated 7.5% unreacted starting material, 41.3%trans-1,1,1,3,5,5,5-heptafluoropent-2-ene and 47.2 ofcis-1,1,1,3,5,5,5-heptafluoropent-2-ene, corresponding to a combinedyield of the olefins of 71% and a CF₃ CH₂ CF₂ CH₂ CF₃ conversion of 95%.GC-MS of the olefin isomers were identical and had fragments at m/e 196(parent), 177 (P-F), and 113 (P-CH₂ CF₃).

The crude mixture of the above olefins was 60.3 g, of 79% purity (theremainder being primarily unreacted CF₃ CH₂ CF₂ CH₂ CF₃. The actualweight of the olefin isomers was therefore 47.6 g, 0.243 mol). This wasstirred at room temperature with 0.39 g of 5% Rh on carbon under ahydrogen atmosphere of 20-40 psig. After 6 days, hydrogen uptake ceasedand the catalyst was filtered. Fractional distillation through a 6-inchpacked (0.16-inch Ni turnings) column gave 24.3 g (48.6%) of1,1,1,3,5,5,5-heptafluoropentane, bp 85°-88° C. ¹ H NMR (CDC13): δ 5.12apparent d of heptets (overlapping tt resulting from coupling to 2 setsof diastereotopic CH_(a) H_(b) hydrogens), J=48 and 4 Hz, 1 H), 2.5 (m,4 H); ¹⁹ F NMR: -65.0 (6 F), -183.9 (1 F) ppm; ¹³ C NMR; 125 (CF3, dq,J_(CF) =276 and 4 Hz), 82 (CHF, d of heptets, J_(CF) =176 and 3 Hz),39.8 (CH₂, dq, J_(CF) =30 and 23 Hz) ppm, bp 85°-88° C., % F=67.

EXAMPLE VI

Performance studies are conducted wherein metal coupons are cleanedusing the compounds of Table I as solvents. The metal coupons are soiledwith various types of oils and dried so as to partially simulateconditions which occur while machining and grinding in the presence ofthese oils.

A test tube with condensing coils near its lips is used in thisexperiment. Each solvent is boiled in the test tube and condensed on thecoils to provide adequate vapor. The condensed solvent is dripped backinto the test tube.

The metal coupons are held in the solvent vapor and then vapor rinsedfor a period of 15 seconds to 2 minutes depending upon the oilsselected. Cleanliness (i.e. total residual materials left aftercleaning) of the coupons is determined by measuring the weight change ofthe coupons using an analytical balance. The results indicate that thesolvents of Table I are effective solvents, removing substantially allof the soil from the coupons.

EXAMPLE VII

Performance studies were conducted wherein metal coupons were cleanedusing various HFC solvents. The metal coupons were soiled with varioustype of oils. These metal coupons were degreased in a small beaker withcondenser coils around the lip to condense solvent and reduce losses andalso to generate vapors to rinse the coupons.

Metal coupons are held in the solvent vapor and then vapor rinsed for aperiod of 15 seconds to 2 minutes depending upon the oils selected.Cleanliness testing of the coupons are done by measurement of the weightchange of the coupons using an analytical balance to determine the totalresidual materials left after cleaning.

    __________________________________________________________________________    Solvents                                                                            Methyl                                                                  Soil  Chloroform                                                                           CFC-113                                                                             CF.sub.3 CH.sub.2 CF.sub.2 CH.sub.2 CF.sub.3                                            CF.sub.3 CF.sub.2 CH.sub.2 CH.sub.2 CF.sub.2                                  CF.sub.3    CHF.sub.2 CHFCHF.sub.2               __________________________________________________________________________    Petroleum                                                                           98     93    57        55          25                                   Oil                                                                           Synthetic                                                                           95     32    73        28          75                                   Oil                                                                           __________________________________________________________________________

EXAMPLE VIII

The compatibility of various plastics in the solvents of Table I ismeasured by immersing the plastic in the solvent for a period of 2 to 10minutes which stimulates at typical cleaning time for these materials insolvents. The visual observations are reported in Table II below. Forpurposes of this experiment "No Change" meant that visually no change inthe color, size, texture and weight of the plastic was observed.

                  TABLE II                                                        ______________________________________                                        MATERIAL      OBSERVATION                                                     ______________________________________                                        ABS           No Change                                                       Acrylic       No Change                                                       PVC           No Change                                                       Nylon 66      No Change                                                       HDPE          No Change                                                       Polypropylene No Change                                                       HIPS**        No Change                                                       Polycarbonate No Change                                                       ______________________________________                                         *High density polyethylene                                                    **High impact polystryene                                                

The invention has been described with reference to certain preferredembodiments. However, as obvious variations thereon will become apparentto those skilled in the art, the invention is not to be considered aslimited thereto.

What is claimed is:
 1. A hydrofluoroalkane selected from those of thefollowing formula:

    CHF.sub.2 --X--(CHF).sub.n --X--Y

wherein X is selected from the group consisting of CHF, CF₂ and CH₂, Yis CH₃, and n is 0, 1 or 2.